1. Field of the Invention
This invention relates to a seatbelt webbing retracting device for retracting a webbing fastened to an occupant in an emergency of a vehicle, used in a seatbelt system for protecting the occupant in an emergency of the vehicle.
2. Description of the Prior Art
In general, a webbing is fastened to an occupant by a seatbelt system, whereby the webbing restrains the occupant in an emergency of a vehicle, so that the occupant can avoid colliding with dangerous protrusions. The webbing is wound at one end thereof into a retractor and constantly subjected to a tension of a retracting force of the retractor. However, the windup force is made to be a comparatively weak biasing force for the purpose of obviating an oppressive feeling of the occupant. Hence, there is formed a clearance space between the webbing and the occupant, and, there has been pointed out such a disadvantage that, in the case that a takeup shaft of the retractor is locked to restrain the occupant in an emergency of vehicle such as a collision, the restraint to the occupant by the webbing becomes unsatisfactory until the aforesaid clearance space is decreased, thereby unabling to obtain a satisfactory restraining effect to the occupant by the webbing.
Because of this, such a device has been proposed that the webbing is retracted by use of an explosive force of gunpowder or the like in an emergency of the vehicle. However, in the case that a danger is caused by use of the gunpowder, it is difficult to control the explosive force of the gunpowder and it is impossible to reuse the device.